The broad objective is to elucidate the effect of Phage T5 infection on the metabolism of nucleotides in E. coli. At T5 mutant unable to induce dTMP Kinase will be characterized to determine why the lack of this enzyme reduces DNA synthesis in vivo. Mutants unable to induce thymidylate synthetase or ribonucleotide reductase will be isolated, and the effect of mutations in these three enzymes on DNA synthesis in plasmolysed cells will be determined. The intermediates produced during degradation of host DNA after T5 infection will be characterized to determine why the breakdown products are not reincorporated into phage DNA. The fate of E. coli DNA polymerase I after T5 infection will be characterized to determine whether the structure, activity, or physical locaton of this enzyme is altered after infection.